HCI NoSQL Databases 1. Introduction to NoSQL

NoSQL Databases CPDD Computer Education Unit Version: Feb 2019 1 Name: __________________________ ( ) Class: _________ Date: _________ Lesson 1: Introduction to NoSQL Instructional Objectives: By the end of this task, you should be able to:  Understand how NoSQL database management system address the shortcomings of relational database management system (SQL)  Explain the applications of SQL and NoSQL  Use MongoDB shell to create, edit and remove databases Why learn NoSQL? Relational databases (commonly referred as SQL databases) work well with structured data since each table's schema (the precise description of the data to be stored and the relationships between them ) is always clearly defined. However, with the increasing number of ways to gather and generate data , we often need to deal with unstructured data. For example , a convenience store that frequently refreshes the services it provides may sell both mobile phones as well as groceries. To run the store, information about both mobile phones (e.g., model names and prices) and groceries (e.g., prices and descriptions) need to be stored. In the future, the store may also start selling mobile phone subscription plans as well. Storing all this data in the same relational database may not be easy. In this case, non-relational databases, also referred to as NoSQL databases, can offer a better choice. There are four main types of NoSQL databases: key -value databases, document databases, wide-column databases and graph databases. For the syllabus, we focus on MongoDB, a type of document database. Document databases work like a hash table, but each key ca n point to an embedded key -value structure, also known as a document, instead of just a single value. (Recall that in a hash table, each key points to a single value or data item.) How NoSQL addresses shortcomings of relational databases  Relational databases have a predefined schema that is difficult to change. Even if you wish to add a field to a small number of records, you still need to include the field for the entire table. Therefore, it can be difficult to support the processing of unstructured data using relational databases compared to NoSQL databases.  Unlike NoSQL databases, relational databases do not usually support hierarchical data storage where less frequently-used data is moved to

NoSQL Databases CPDD Computer Education Unit Version: Feb 2019 2 cheaper, slower storage devices. This means that the cost of storing data in a relational database is more expensive than storing the same amount of data in a NoSQL database.  Relational databases are mainly vertically scalable while NoSQL databases are mainly horizontally scalable. Vertically scalable means that improving the performance of a relational database server usually requires upgrading an existing server with faster processors and more memory. Such high - performance component